December 15th 2022 an earthquake swarm appeared out of Langanes at Bakkaflóadjúp near the Northeast coast of Iceland. Some 40 years ago earthquakes were also measured there. The earthquakes occur exactly on the line for the main division between large scale convection rolls as they extend all the way from equator. Not many words are needed to explain this, just two simple drawings, one from the National Met Office, and one map with the main division drawn on it, map base from National Land Survey of Iceland.
There are actually two layers represented with this line, one is the eastern side of the convection roll which creates the Reykjanes Ridge. That convection roll is then subducted by the northern more rolls, so it is found at considreable depthe at these latitudes of the earthquake area. But the same is true for the large scale structures of the lower mantle, and effect from there are expected to take part in triggering these earthquakes. The large scale rolls intersect each other, the equatorial roll being subducted, and the lower mantle division line is therefore found near the boundary between mantle and core.